Helical-hearth furnace



Jan. 8 1924.

E. BRACQ-LAURENT HELICAL HEARTH FURNACE Filed April 20, 1.922

2 Shuts-Shoot 2 Patented Jan. 8, 1924.

Q usmrro. sit-Ares PATENT reimco rnuannr, or PARIS, FRA CE; 1

HE'LICAL-HEARTH FURNACE.

Applicatlon filed' April 20, 1922. Serial No. 555,735;

To all whom it may concern:

Be it known thatI, EMILE BRAC -LAUR- ENT, a citizen of the Republic of Fra-nce residing in Paris, France, have invented certain new andv useful Improvements m rising and descending movements limited in their advance, obtained byvarious:v known by previous patents.

This invention comprises a construction means by means of which the various movements.

may be produced, the number ofmechanical elementsin the said construction being reduced to a minimum, whilst at" the same time ensuring eflicient operation of the furnace, and reduction of the supervision and upkeep of the parts.--

The construction according. to this invention is shown in the accompanying drawings' in which- Figure 1- is an elevation, partly in sectlon of theup'per' part of the furnace where the Whole of the operating mechanism' is arranged, and

Figure 2 is a plan lookingfrom the top mechanism. I

Fig. '3 is a "detail sectional elevation and Fig; '4 a detail elevation portions of the device;

of the rotating platform" supporting the:

In helical hearth furnaces designed by the applicant, thecentral shaft 1 carrying the scraper arms 2 revolving the material in the furnace, receives all its movements from a shaft 3 forming an extension of the central shaftl and placed outsidethe furnace, either at the top or at the bottom,

according to the arrangement adopted.

This device still remains the same, but

according to this invention a rotating platform 5 provided 'at the circumference with helical teeth-Gmeshing with a worm '71s mounted on a fixed circular frame 4." On the top of the said'platfo'rm 5 is mounted an electric motor 8 which drives, by means of certain of a worm, a worm 'wheel 9,: (Figure 2 enclosed in a case 10 and mounted onthehorizontal spindle: 11.1 This spindle 'is sup ported in two bearings 12 and 13 mounted on the rotating platform 5, and produces two movements which. are transmittedto the: shaft 3, and consequently to: the central shaft. 1 and scraper. armsv 2, 2:,secured to:

the shaft 3. 1 1 4 By means of a crank disc-14, connectingrod 15and a guide-support 16, an angular movement is produced the 'extent of'which can: be modified by shiftingthe position of the. adjustable crank pin- 17 The rod'l5 is connected to a bridle18 which, by means of two fixed projections 1 9 and 19 slidingin two straight vertical grooves 20 pro vided in the shaft 3, transmits to thezlat ter the angular movement imparted toit by the connecting crank pin 17-. p i r The second movement produced by the spindle 11, raises'andlowersthe shaft 3 and consequently the central shaft 1 and its scraper arms by means of "an eccentric 21,

the rod 22 of which drives by means-of its head 23, arocker 24 with trunnionsflfi. The trunnions 26 are mounted in a collar 27 rotating between the flangesof a large nut 28 screwed: on the shaft 3 wliich is: provided with helical grooves '29 which constitutea kind of thread of the same pitch as-that of the refractory-hearths in thennterior' of the furnace, on which are 'stirred and moved the materials under treatment. The rocker 24 oscillates on a pin 25 which is common to the lever 40 the-said pin resting at its ends on supports secured below the circular rim or platform 5';

The nut'28 is prevented from-moving ci rcularly by two rods 30: secured'to it and}- sliding in two fixed guides 31. The said operated by the rocker 24. 1

The nut 28 has a threadcorresponding nut, however rises and descends on' being to the grooves 29, in the same manner as wid -re thethread of a; bolt nut, and'the entersthe helical groove 29; It will be understood from' gage with the helical fgrooves 29 0f the shaft 3, will raise and lowent'he grooved shaft 3 andtherefore the central shaft' l with its'arms 2.;

rod 15- attachedto "the,

V the preceding that at eachrevo'lution of "the eccentric 21, the large nut 28, the threads of wh-i ch en- Obviously, if the nut 28 is caused to rise or descend bymeans of the rocker 24, the

central. shaft 1 carrying the arms 2 and rigidly secured to the shaft 3 must necessarily follow the movement imparted.

It will be seen, therefore, that in this device a single shaft 11 produces two essential moveme'nts imparted to the grooved shaft 3 and consequently to the central shaft 1 with its arms 2 and 2, firstly, the angular -movement, and secondly, the up and down movement. A third movement however, takes place simultaneously which movement is the progressive raising and lowering of the centralshaft 1 during the first two movements described, in harmony with the pitch of the refractory hearth of the furnace through which it has to travel, which pitch is similar to that inscribed on the grooved shaft 3.

The worm 7 which drives the helical teeth 6 of the circumference of the rotating platform 5, is driven by the spindle 32 to which it is keyed and which is driven by pulleys 33 and 34 the direction of movement being reversed by means of clutches operatively connected to a rod 36. Thisworm 7 rotates the platform 5 which carries the bridle 18 which rotates the. shaft 3.

- The nut 28 which cannot rotate on account of the fixed guides 30 and 31,- forces thegro'oved shaft 3 to rise or descend according as' the bridle 18 screws or unscrews it.

The direction is reversed by means of tappets 37 and 38 suitably arranged so as to act on the clutches by the rods 36 and 35.

.A principle of helical hearth furnaces is to stirand advance the material being roasted on the hearths during the upward movement of the scraper arms 2 and 2.

Atthe end of this movement, the direction and 34, and the central shaft 1 effects a period of descent during which the up and down movements must cease, in order that the scraper arms 2-.may cease their action which otherwise would be injurious.

. Moreover it is necessary that the scrapers 2 and 2 lowered with the shaft 1, should in this downward movement be brought over the material which, in passing, they have treated and advanced. To that end the eccentric rod 22 is connected with its head 23 The action of the connecting rod 22 which,

causes the central shaft 3 and the arms to rise and descend is stopped by means of the rod 41 provided with a tappet 44 which latwhich it is secured, so that the lever 40, the

end of which is securedto the connecting rod 22, is turned by the tappets on the latter.

It is obvious that the rising and descending movements will be produced during the whole rotation of the platform in order to displace the material in thelfurnace.

.-Without the electric motor, complicated mechanisms-such as are in fact used for known furnaces ofthe presentkindwouldv be necessary to control themovements on a rotatingplatform, so that theidea of using an electric motor constitutes a great improvement. I I I During the rise and descent, the head 23 strikes against the portion 6, b of part 39 and as the said part 39. is integral with the rocker 24, the latter is, compelled to rise and descend at eachrevolution ofthe connect ing rod 22. However, when the head 23 of the rod 22 is drawn into the'opening ,43 by the rod 39, its action is stopped as before stated and the rocker 24 rendered immovable in any desired'position .by the stops ofv the nut 28. I

It should be understoodthat thevrod 22.

moves in the centre of the two lateral parts of the opening 43.

A, A, are the ends or journals of the crosshead, which ends are pivotedto the rod 22 and normallyrest onpartv B, Bfof the-part 39, and which are then released inthe lateral opening, 43 when it is desiredto stop the action of the connecting rod 22. In fact, whenever the-; eccentric 21 descends, it lowers with the head 23 the rocker 24 which thus raises the arms 2fabove the material being treated during the period of descent, whilst whenever the eccentric pulley 21 rises, its action-is cancelled by the head 23 moving in the opening 43 into which it has been brought by the. rod 41 and the connecting rod 39. a 1

This movement of the eccentric rod 22 and its head 23operative orinoperative is thus obtained in a practical and reliable manner, with great facility of regulation or adjustment, and with a minimum number of parts.

case, whether there be-one or more helical hearths, or whether there be agreater or less number of scraper arms 2 between which the rotation of the grooved shaft 3-is divided. Owing to the operation of the tappet This movement may belobtainedl inevery 42, the action Or inaction of 22 and 23 depends on the desired up or down movement of the shaft 3.

It is further possible to produce by the bottom end of the rod 41 the throwing into or out of gear of the pulleys 33 and 3 1 by means of the clutches on which the rod 41 acts by means of bell crank levers.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a furnace with a helical hearth having a central shaft, a rotating platform, and scraper arms, means producing the angular movement and the up and down movement of the central shaft, comprising a single spindle driven by an electric motor mounted on the rotating platform of the furnace.

2. In a furnace as claimed in claim 1, means for producing the angular movement, comprising a crank disc mounted at one end of a driving spindle and having a crank pin the position of which may be adjusted to suit the amplitude of movement to be transmitted, the said movement being transmitted to a bridle provided with two projections engaging with two corresponding grooves of the shaft and thus transmitting the movement to it.

3. In a furnace as claimed in claim 1, means for producing the up and down movement of the shaft, and scraper arms, comprising an eccentric mounted on the single driving spindle and operating a rocker, one of the trunnions of which is secured to a collar rotating about a large nut which is adapted to slide round the shaft but cannot rotate, the said nut by its rise or descent rotating the said shaft and consequently raising or lowering the shaft carrying the scraper arms.

4:. In a furnace of the character described, the combination with a central shaft, and scraper arms thereon, of a rotatable platform provided with circumferential helical teeth, a worm engaging with said teeth to effect the rotation of the platform, means for rotating the worm in either direction, and means for producing an angular movement and an up and down movement of the central shaft comprising a single spindle driven by an electric motor mounted on the said platform.

5. In a furnace of the character described, the combination with a central shaft and scraper arms thereon, of means for producing an angular movement and an up and down movement of the central shaft, and means for effecting the descent of the shaft and of the scraper arms automatically comprising a tappet secured to the shaft, an eccentric, a rod operated thereby, a rocker operated by said eccentric rod, a pivoted lever carrying a balance weight, a connecting rod between the weighted lever and the eccentric rod, and a vertical rod operated by the aforesaid tappet, the said pivoted lever being operated by the said vertical rod so as to cancel the movement of the aforesaid connecting rod.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

EMILE BRACQ-LAURENT.

Witnesses GEORGE FAU I I, ROGER RAGUER. 

